The invention relates to electrical boxes and more particularly to electrical boxes including clamping devices used for anchoring or clamping electrical cables to the electrical boxes.
Various electrical boxes have been utilized which provide some means for securing an electrical cable to the box so as to prevent inadvertent disconnection or disengagement of the cable from the box. Various electrical codes and standards have been applied to these electrical boxes. Recently, new requirements have been suggested for nonmetallic outlet boxes and certain electrical cables. These new requirements are concerned with securing electrical cables to the box such that the cables cannot readily be unintentionally removed. The following is representative of these requirements:
"25. Clamps for Nonmetallic-Sheathed Cable PA0 25.1 A nonmetallic-sheathed-cable clamp shall secure the cable so that it will withstand for 5 minutes a direct pull of 60 pounds (267 N) without (1) damage to the insulation, (2) displacement of more than 1/8 inch (3.2 mm), or (3) loosening so that the cable can be readily removed by bending or flexing when the force is removed. The pull shall be applied between the cable and a box in which the clamp is mounted in the intended manner. PA0 25.2 In preparing the sample for the test described in paragraph 25.1, the cut end of the cable sheath is to be in contact with the stop, if one is provided; if no stop is provided, the cut end of the sheath is to extend approximately 1/4 inch (6.4 mm) beyond the clamp. The wires of the cable are to be allowed to project approximately 6 inches (152 mm) inside the box. Nonmetallic sheathed cable with a plastic outer jacket, or impregnated outer braid, is to be used in conducting the secureness test on a clamp for use with a No. 14 AWG (2.1 mm.sup.2) 2-wire cable. The cable is to have a minor axis of 0.210-0.285 inch (5.33-7.24 mm) and a major axis of 0.390-0.470 inch (9.91-11.94 mm). A screw that can be tightened with a screwdriver is to be tightened as specified in paragraph 8.5. See paragraph 77.10." UL 514C 25 (1981).
Various methods heretofore have been used to secure electrical cable in accordance with the above requirements. Some of the boxes use clamps retained by screws within the box to grip electrical cables inserted through box openings. These electrical boxes have the shortcoming that installation is relatively cumbersome and tightening the clamps requires use of a screwdriver in the small confines of an electrical box.
Another variety of electrical box eliminates the screws and instead uses wedges which must be forced into place after the electrical cable is inserted into the box. These wedges are also difficult to manipulate within the confines of the box. In addition, provisions must be made in distributing and selling the boxes for either packaging the wedges such that they remain with the rest of the box or for providing for the separate distribution of both boxes and wedges.
Another variety of electrical box utilizes a clamp attached to the box by a relatively pliant neck. In this variety of box, the neck is bent, the electrical cable is inserted into the box, and the clamp is then set by pressing it against the cable. Like other electrical boxes, this box has the shortcoming that the clamp must be manipulated within the box to secure the cable.
It is therefore highly desirable to provide an improved electrical box. It is also highly desirable to provide an improved electrical box which retains electrical cables without the use of screws. It is also highly desirable to provide an improved electrical box in which clamps or wedges do not have to be tightened or set. It is further highly desirable to provide an improved electrical box by which electrical cables can be retained therein totally from the exterior of the box and without manipulation within the box. It is further highly desirable to provide an improved electrical box which may be shipped without the fear of loss or special packaging or distribution of the wedges or clamps.
It is still further highly desirable to provide an improved electrical box which is easy to use and which presents little risk of damage to the electrical cable and the electrical box.
It would finally be highly desirable to provide an improved electrical box which meets all of the above-desired features.
It is a feature of the improved electrical box of the invention to retain electrical cables without the use of screws or other small fasteners by means of resiliently deflectable or deformable wedge elements and upstanding retainers. This gives the improved electrical box of the invention the advantages of easier assembly and use.
It is also a feature of the improved electrical box of the invention to provide resiliently deflectable or deformable wedge elements which grip the electrical cable without having to be set. This gives the improved electrical box of the invention the advantage that the step of setting the clamps and all other cumbersome manipulations within the box are eliminated in utilization of the electrical box of the invention.
The improved electrical box of the invention further provides the feature that wedge elements are retained in the electrical box by retainers and the box walls. This reduces the risk of loss of wedges or clamps during shipment and provides the improved electrical box of the invention the advantage that special packaging or distribution is unnecessary.
The invention still further provides an improved electrical box which has the feature that wedge elements have upper portions and adjoining shoulders which are resiliently deflectable or deformable within a limited range by insertion of the electrical cable, so that upon insertion, the electrical cable is wedged between the upper portion and the box itself. This gives the improved electrical box of the invention the advantage that the electrical cable may be easily inserted as one step and with little risk of damage to the electrical cable.
The invention meets all of the above-described objects and provides all of the above features and advantages by providing an improved electrical box which includes an enclosure. The enclosure has a peripheral wall and a bottom. The peripheral wall has a first plurality of openings. The bottom has a second plurality of upstanding retainers adjacent the openings. A third plurality of wedge elements is disposed between the retainers and the peripheral wall adjacent the openings. The wedge elements are resiliently deflectable by insertion of electrical cables through the respective openings whereby insertion of the electrical cables wedges the electrical cables between the wedge elements and the peripheral wall.